The 3rd Generation Partnership Project (3GPP), which is a standardization project, standardized the Evolved Universal Terrestrial Radio Access (hereinafter referred to as “E-UTRA”), in which high-speed communication is realized by adopting an orthogonal frequency-division multiplexing (OFDM) communication scheme and flexible scheduling using a unit of prescribed frequency and time called resource block.
Moreover, the 3GPP discusses Advanced E-UTRA, which realizes higher-speed data transmission and has upper compatibility with E-UTRA. The E-UTRA is a communication system based on a network in which base station devices have substantially the same cell constitution (cell size), and on the other hand, in the Advanced E-UTRA, discussion is made on a communication system based on a network (different-type radio network, heterogeneous network) in which base station devices (cells) having different constitutions coexist in the same area. Note that, the E-UTRA is also referred to as “LTE (Long Term Evolution)”, and the Advanced E-UTRA is also referred to as “LTE-Advanced.” Moreover, LTE can be a general term including LTE-Advanced.
In a communication system where cells (macro cells) having large cell radii and cells (small cells) having smaller cell radii than those of the macro cells coexist as in a heterogeneous network, a carrier aggregation (CA) technique and a dual connectivity (DC) technique are regulated in which a terminal device performs communication by connecting to a macro cell and a small cell at the same time (NPL 1).
Meanwhile, in NPL 2, discussion is made on Licensed-Assisted Access (LAA). In the LAA, an unallocated frequency band (unlicensed spectrum) used by a local area network is used for LTE, for example. Specifically, the unallocated frequency band is configured as a secondary cell (secondary component carrier). The secondary cell used as the LAA is assisted in connection, communication and/or configuration, by a primary cell (primary component carrier) configured in an allocated frequency band (licensed spectrum). The frequency band available in LTE is extended by the LAA, and hence, broadband transmission is possible. Noted that the LAA is also used in a shared frequency band (shared spectrum) shared among predetermined operators.